Gas pressure monitoring system for GIL using fiber-optic gas density sensors

The authors have developed a fiber-optic gas pressure monitoring system with new gas density sensors for detecting the leakage of insulation gas of gas-insulated transmission lines (GILs). In this system, the gas pressure of over one hundred gas compartments can be monitored with several optical fibers and without electric power supply to the sensors. This simple and highly reliable system enables speedy gas leakage detection, allowing one to take appropriate measures before reaching its critical pressure. The developed sensor makes a mechanical bend of an optical fiber when there is gas leakage, and causes optical transmission loss as the detected signal. Using a conventional optical time domain reflectometer with these sensors, a multi-point sensing system can be constructed. In this paper, the authors report the principle of this sensor and the design of the monitoring system for Japan´s Shinmeika-Tokai GIL